Improvement of oxidation behaviour of dense silicon nitride by surface modification

Taut, Chr.; Herrmann, Matthias; Grosse, G.; Thiele, P.; Gogotsi, Yu.G.

doi:10.1016/0955-2219(94)90032-9

Cited by 4 publications

(1 citation statement)

References 6 publications

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“…In this way, the outward diffusion of the cations from intergranular phase to oxide becomes the rate-controlling step. For the sake of building the protective surface the oxide ceramics, noble metals and pure silicon nitride were coated on the surface of the silicon nitride ceramics containing sintering additives [19][20][21]. Aluminum implantation was also expected to re-build the protective nature of the oxide formed on the HIP Si 3 N 4 by neutralizing the detrimental effect of the network modifiers such as Mg, Na, etc [18,[22][23].…”

Section: Introductionmentioning

confidence: 99%

Effect of Cation Extraction on the Oxidation Resistance of Si3N4

Yuan²,

Zeng³

et al. 2007

KEM

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A new method called cation extraction process has been applied to improve the oxidation resistance of silicon nitride ceramics with sintering additives. It is found that the high temperature oxidation rate of the Si3N4 ceramic treated by the process decreased remarkably in contrast to the oxidation rate of the Si3N4 without the process. The oxidation rate of Si3N4 ceramics with the cation extraction process is reduced more than 50% comparing with that of the Si3N4 ceramics without the process. The morphological characteristic and phase composition of the oxides were analyzed by means of SEM and XRD. The oxidation rate of silicon nitride after cation extraction treatment is determined by the quality of the “purified layer” formed below the pre-oxide scale. Thicker oxide layer formed in pre-oxidation, higher extraction temperature and longer extraction time are helpful to form a good “purified layer”.

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Section: Introductionmentioning

confidence: 99%

Effect of Cation Extraction on the Oxidation Resistance of Si3N4

Yuan²,

Zeng³

et al. 2007

KEM

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Formation of an α‐SiAlON Layer on ß‐SiAlON and Its Effect on Mechanical Properties

Jiang

Baek

Lee

et al. 1998

Journal of the American Ceramic Society

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We have developed a technique for in situ formation of an ␣-SiAlON layer on sintered ␤-SiAlON. The technique consists of packing a powder compact of ␤-SiAlON composition with ␣-SiAlON composition powder, presintering, and sintering. Using this technique, it is possible to control the thickness of the layer by changing the presintering conditions during heating to a sintering temperature. The introduction of an ␣-SiAlON layer increases the surface hardness and improves the wear and oxidation resistance, with a moderate reduction of flexural strength. The surface modification of ␤-SiAlON may provide opportunities of wider application of ␤-SiAlON to wear-and oxidationresistant components.

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Identification of oxidation mechanisms in silicon nitride ceramics by transmission electron microscopy studies of oxide scales

Backhaus‐Ricoult

Gogotsi

1995

J. Mater. Res.

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Additive-free HIPSN and Y 2 O 3 + Al 2 O 3 -doped HPSN are oxidized in air in the temperature range from 1300 to 1500 °C. TEM, SEM, EDS, and XRD are used to analyze the composition and microstructure of the oxide scales in order to determine the oxidation mechanisms. HIPSN exhibits excellent resistance to oxidation in air at temperatures up to 1480 °C due to the formation of a protective silica (cristobalite) scale. No formation of Si2N2O and oxygen-enriched /3'-Si 3 N 4 under the silica layer is observed for materials densified without additives. Oxidation rates of additive-containing HPSN are more important due to the formation of a viscous aluminosilicate phase, which easily penetrates along the grain boundaries in the material. Silicon nitride grains in contact with the viscous phase first become enriched in aluminum and oxygen and are then dissolved in the glassy phase. No Si2N2O intermediate layer is formed. The finding of the decisive role of the aluminosilicate in the oxidation process allows one to explain inconsistencies observed in the oxidation kinetics of silicon nitride ceramics. Effects of sintering additives, WC contamination and temperature on the oxidation mechanisms, and structure of oxide scales are discussed.

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Improvement of oxidation behaviour of dense silicon nitride by surface modification

Cited by 4 publications

References 6 publications

Effect of Cation Extraction on the Oxidation Resistance of Si<sub>3</sub>N<sub>4</sub>

Effect of Cation Extraction on the Oxidation Resistance of Si<sub>3</sub>N<sub>4</sub>

Formation of an α‐SiAlON Layer on ß‐SiAlON and Its Effect on Mechanical Properties

Identification of oxidation mechanisms in silicon nitride ceramics by transmission electron microscopy studies of oxide scales

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